Voltage and power balance strategy without communication for a modular solid state transformer based on adaptive droop control.
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Date
2018
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Abstract
Solid State Transformers (SST) are attracting considerable attention due to their great
application potential in future smart grids. It is an essential technology capable of promoting
the modernization of the electric power distribution system and it is considered a key element
for interfacing future microgrid systems to medium voltage utility grids, allowing plug-and-play
integration with multiple renewable energy sources, storage devices and DC power systems. Its main
advantages in relation to conventional transformers are substantial reduction of volume and weight,
fault isolation capability, voltage regulation, harmonic filtering, reactive power compensation
and power factor correction. A three-stage modular cascaded topology has been considered as
an adequate candidate for the SST implementation, consisting of multiple power modules with
input series and output parallel connection. The modular structure presents many advantages,
e.g., redundancy, flexibility, lower current harmonic content and voltage stress on the power switches,
however component tolerances and mismatches between modules can lead to DC link voltage
imbalance and unequal power sharing that can damage the solid state transformer. This paper
proposes a decentralized strategy based on adaptive droop control capable of promoting voltage and
power balance among modules of a modular cascaded SST, without relying on a communication
network. The behavior of the proposed strategy is assessed through a MATLAB/Simulink simulation
model of an 100 kVA SST and shows that power and voltage balance are attained through inner power
distribution of the SST modules, being transparent to elements connected to the transformer input
and output ports. Besides that, real-time simulation results are presented to validate the proposed
control strategies. The performance of embedded algorithms is evaluated by the implementation
of the SST in a real-time simulation hardware, using a Digital Signal Processor (DSP) and high
level programming.
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Keywords
Microgridvoltage balancing control, Decentralized control, Real time simulation
Citation
RODRIGUES, W. A. et al. Voltage and power balance strategy without communication for a modular solid state transformer based on adaptive droop control. Energies, v. 11, n. 7, p. 1802, 2018. Disponível em: <https://www.mdpi.com/1996-1073/11/7/1802>. Acesso em: 19 fev. 2019.